The present invention relates generally to a medical instrument for measuring the strength of the tongue, and in particular, to an instrument for measuring contact pressures between the tongue and the hard palate for the diagnosis and treatment of swallowing disorders.
Tongue strength decreases as a person ages. A sufficient loss of tongue strength can lead to swallowing disorders, which in turn can cause physical disease in the individual as well as deprive the individual of the pleasure of eating. Nevertheless, research has shown that exercise of the tongue by pressing it against the hard palate for a number of repetitions each day at a given force level may increase tongue strength and may help improve the swallowing function.
A number of methods exist to measure tongue strength. Qualitatively the clinicians may have a patient press against a tongue depressor with his or her tongue.
The Tongue Force Measurement Systems (TOMS) developed by S. N. Robinovich, et al., provides a more accurate alternative. The TOMS device employs a custom built, dental-putty mouthpiece to align a user""s tongue with a cantilevered beam. Force on the beam is detected by strain gauges sensing beam deflection. The TOMS device requires that the patient""s mouth be open at about 40% of its maximum limit. A substantial portion of the TOM""s mechanism extends outside the patient""s mouth and is supported by an adjustable arm.
The National Institutes of Heath also produces a device to measure tongue strength, termed the APLSILT system. This device, which is commercially available from ACW Research Incorporated of Chatham, N.J., uses disposable tongue depressor mounted on a load cell held by a mechanism on an adjustable table. Only the tongue depressor is placed within the patient""s mouth with the remaining portions of the mechanism being outside of the patient""s mouth and supported on the table.
A Lingual Force Transducer, described in the paper Force Production of the Genioglossus as a Function of Muscle Length in Normal Humans, by B. F. Sha, et al. Journal of Applied Physiology, 88, (5), 1678-84, includes a compact housing that may be inserted into the patient""s mouth and which exposes a balloon on its leading surface. The balloon is connected to a pressure transducer and the device measures the force exerted by the tip of the tongue pressing in a direction out of the mouth, on the balloon.
The Iowa Oral Performance Instrument (IOPI), described in the article Swallowing And Tongue Function Following Treatment For Oral And Oropharyngeal Cancer, by Lazarus, et al. 2000, Journal of Speech, Language and Hearing Research 43, 1011, is an air filled bulb, freely moveable within the mouth and attached to a hose that may be connected to a pressure transducer outside of the mouth. The transducer provides a light emitting diode display that indicates pressure on the bulb as a proportion of a manually set maximum to provide visual feedback to motivate the patient in an exercise program.
The present invention provides a device that allows placement of thin pressure sensors adjacent to the hard palate to measure tongue strength in an environment that closely matches the environment of normal swallowing, particularly with respect to mouth opening and tongue placement. The present invention also provides an in-mouth system that aligns itself against other mouth structure for repeatable and accurate measurements over the course of a diagnosis or exercise program. Thus, the invention is usable both by patients and healthy individuals who can be helped by an exercise program (henceforth collectively: xe2x80x9cclientsxe2x80x9d).
Specifically, then, the present invention provides an apparatus for measuring the pressure exerted by a client""s tongue against the hard palate. The invention includes a sensor support surface sized to fit closely adjacent to the hard palate and a mouth registration means attached to the sensor support and engaging the mouth structure to reproducibly locate the sensor support within the client""s mouth. At least one electronic pressure sensor is positioned on a lower surface of the sensor support wholly within the mouth and facing the tongue to be activated thereby; and, an electronic annunciator communicates with the electronic pressure sensor to provide an indication to the client of the pressure measured by the electronic pressure sensor upon pressure by the tongue.
Thus, it is one object of the invention to provide a sensor system that allows the tongue pressure to be measured with the tongue positioned adjacent to the hard palate as during swallowing and that further allows the mouth to be closed to better approximate the natural mouth position during swallowing.
It is another object of the invention to provide these benefits in a system that presents an indication to the client for encouragement and feedback during training exercises.
Two electronic pressure sensors may be positioned on the lower surface of the support displaced along a midsagittal plane.
Thus, it is another object of the invention to provide finer resolution of measurement to the pressures between the tongue and hard palate such as may provide better insight of the swallowing process for a particular client.
The mouth registration means may include at least one surface engaging the client""s teeth, for example, like the structure of a dental retainer, or as an interdental plate fitting between the client""s teeth to be clamped thereby, allowing substantially full closure of the client""s mouth for swallowing.
Thus it is another object of the invention to provide a simple registration means for the pressure sensors, such as allows reproducible measurement of tongue/hard palate pressures without the need for extensive mechanisms that must be independently supported or that limit the positioning of the client""s head.
The mouth registration means may include either additionally or alternatively at least one surface engaging the client""s hard palate, for example, a conformal mold of the client""s hard palate.
Thus, it is another object of the invention to provide a registration means that helps to support the forces of tongue/hard palate interaction and that promotes accurate registration at the points of pressure measurement.
When the mouth registration surface is an interdental plate, it may be C-shaped and the sensor support may be a cantilevered arm attached to a point centered on the C of the interdental plate to extend upward from a plane of the C in the direction of curvature of the C.
It is thus another object of the invention to provide a simple structure for the support of the pressure sensors that may be readily adapted to a variety of different mouth sizes. The interdental plate may be a standard heat moldable mouthguard adjustable to conform to the client""s teeth and the cantilevered arm may be adjustable through either bending or replacement to provide the proper depth and height for the client""s mouth.
The electronic annunciator may communicate via conductive cables with the electronic pressure sensor where the cables include a connector for releasably separating the conductive cables into two portions. As mentioned, the sensor support may be removable from the mouth registration means.
Thus, it is another object of the invention to provide a sensor system that may be disassembled for easy cleaning of the mouth contacting parts.
The annunciator may be selected from the group consisting of a lamp, a tone generator, and a digital display. The digital display may provide a display of peak pressure, average pressure, or percentage of a predetermined peak pressure.
Thus is therefore another object of the invention to provide flexibility in communication of the pressure data to the client or the clinician according to the demands of different applications.
The annunciator may provide an indication of a pressure exceeding a predetermined threshold. In one embodiment, the predetermined threshold may be increased according to a predetermined schedule.
Thus, it is one object of the invention to provide a pressure sensing apparatus suitable for use in therapy in which a client is encouraged to provide a given pressure to the apparatus and that pressure is regularly increased in a training regime.
The foregoing objects and advantages may not apply to all embodiments of the invention and are not intended to define the scope of the invention, for which purpose claims are provided. In the following description, reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by way of illustration, a preferred embodiment of the invention. Such embodiment also does not define the scope of the invention and reference must be made therefore to the claims for this purpose.